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media: s5p-mfc: Fix lock contention - request_firmware() once
Driver calls request_firmware() whenever the device is opened for the first time. As the device gets opened and closed, dev->num_inst == 1 is true several times. This is not necessary since the firmware is saved in the fw_buf. s5p_mfc_load_firmware() copies the buffer returned by the request_firmware() to dev->fw_buf. fw_buf sticks around until it gets released from s5p_mfc_remove(), hence there is no need to keep requesting firmware and copying it to fw_buf. This might have been overlooked when changes are made to free fw_buf from the device release interface s5p_mfc_release(). Fix s5p_mfc_load_firmware() to call request_firmware() once and keep state. Change _probe() to load firmware once fw_buf has been allocated. s5p_mfc_open() and it continues to call s5p_mfc_load_firmware() and init hardware which is the step where firmware is written to the device. This addresses the mfc_mutex contention due to repeated request_firmware() calls from open() in the following circular locking warning: [ 552.194115] qtdemux0:sink/2710 is trying to acquire lock: [ 552.199488] (&dev->mfc_mutex){+.+.}, at: [<bf145544>] s5p_mfc_mmap+0x28/0xd4 [s5p_mfc] [ 552.207459] but task is already holding lock: [ 552.213264] (&mm->mmap_sem){++++}, at: [<c01df2e4>] vm_mmap_pgoff+0x44/0xb8 [ 552.220284] which lock already depends on the new lock. [ 552.228429] the existing dependency chain (in reverse order) is: [ 552.235881] -> #2 (&mm->mmap_sem){++++}: [ 552.241259] __might_fault+0x80/0xb0 [ 552.245331] filldir64+0xc0/0x2f8 [ 552.249144] call_filldir+0xb0/0x14c [ 552.253214] ext4_readdir+0x768/0x90c [ 552.257374] iterate_dir+0x74/0x168 [ 552.261360] SyS_getdents64+0x7c/0x1a0 [ 552.265608] ret_fast_syscall+0x0/0x28 [ 552.269850] -> #1 (&type->i_mutex_dir_key#2){++++}: [ 552.276180] down_read+0x48/0x90 [ 552.279904] lookup_slow+0x74/0x178 [ 552.283889] walk_component+0x1a4/0x2e4 [ 552.288222] link_path_walk+0x174/0x4a0 [ 552.292555] path_openat+0x68/0x944 [ 552.296541] do_filp_open+0x60/0xc4 [ 552.300528] file_open_name+0xe4/0x114 [ 552.304772] filp_open+0x28/0x48 [ 552.308499] kernel_read_file_from_path+0x30/0x78 [ 552.313700] _request_firmware+0x3ec/0x78c [ 552.318291] request_firmware+0x3c/0x54 [ 552.322642] s5p_mfc_load_firmware+0x54/0x150 [s5p_mfc] [ 552.328358] s5p_mfc_open+0x4e4/0x550 [s5p_mfc] [ 552.333394] v4l2_open+0xa0/0x104 [videodev] [ 552.338137] chrdev_open+0xa4/0x18c [ 552.342121] do_dentry_open+0x208/0x310 [ 552.346454] path_openat+0x28c/0x944 [ 552.350526] do_filp_open+0x60/0xc4 [ 552.354512] do_sys_open+0x118/0x1c8 [ 552.358586] ret_fast_syscall+0x0/0x28 [ 552.362830] -> #0 (&dev->mfc_mutex){+.+.}: -> #0 (&dev->mfc_mutex){+.+.}: [ 552.368379] lock_acquire+0x6c/0x88 [ 552.372364] __mutex_lock+0x68/0xa34 [ 552.376437] mutex_lock_interruptible_nested+0x1c/0x24 [ 552.382086] s5p_mfc_mmap+0x28/0xd4 [s5p_mfc] [ 552.386939] v4l2_mmap+0x54/0x88 [videodev] [ 552.391601] mmap_region+0x3a8/0x638 [ 552.395673] do_mmap+0x330/0x3a4 [ 552.399400] vm_mmap_pgoff+0x90/0xb8 [ 552.403472] SyS_mmap_pgoff+0x90/0xc0 [ 552.407632] ret_fast_syscall+0x0/0x28 [ 552.411876] other info that might help us debug this: [ 552.419848] Chain exists of: &dev->mfc_mutex --> &type->i_mutex_dir_key#2 --> &mm->mmap_sem [ 552.431200] Possible unsafe locking scenario: [ 552.437092] CPU0 CPU1 [ 552.441598] ---- ---- [ 552.446104] lock(&mm->mmap_sem); [ 552.449484] lock(&type->i_mutex_dir_key#2); [ 552.456329] lock(&mm->mmap_sem); [ 552.462222] lock(&dev->mfc_mutex); [ 552.465775] *** DEADLOCK *** Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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@ -1309,6 +1309,12 @@ static int s5p_mfc_probe(struct platform_device *pdev)
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goto err_dma;
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}
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/*
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* Load fails if fs isn't mounted. Try loading anyway.
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* _open() will load it, it it fails now. Ignore failure.
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*/
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s5p_mfc_load_firmware(dev);
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mutex_init(&dev->mfc_mutex);
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init_waitqueue_head(&dev->queue);
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dev->hw_lock = 0;
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@ -290,6 +290,8 @@ struct s5p_mfc_priv_buf {
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* @mfc_cmds: cmd structure holding HW commands function pointers
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* @mfc_regs: structure holding MFC registers
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* @fw_ver: loaded firmware sub-version
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* @fw_get_done flag set when request_firmware() is complete and
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* copied into fw_buf
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* risc_on: flag indicates RISC is on or off
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*
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*/
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@ -336,6 +338,7 @@ struct s5p_mfc_dev {
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struct s5p_mfc_hw_cmds *mfc_cmds;
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const struct s5p_mfc_regs *mfc_regs;
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enum s5p_mfc_fw_ver fw_ver;
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bool fw_get_done;
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bool risc_on; /* indicates if RISC is on or off */
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};
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@ -55,6 +55,9 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev)
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* into kernel. */
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mfc_debug_enter();
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if (dev->fw_get_done)
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return 0;
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for (i = MFC_FW_MAX_VERSIONS - 1; i >= 0; i--) {
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if (!dev->variant->fw_name[i])
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continue;
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@ -77,6 +80,7 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev)
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}
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memcpy(dev->fw_buf.virt, fw_blob->data, fw_blob->size);
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wmb();
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dev->fw_get_done = true;
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release_firmware(fw_blob);
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mfc_debug_leave();
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return 0;
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@ -88,6 +92,7 @@ int s5p_mfc_release_firmware(struct s5p_mfc_dev *dev)
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/* Before calling this function one has to make sure
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* that MFC is no longer processing */
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s5p_mfc_release_priv_buf(dev, &dev->fw_buf);
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dev->fw_get_done = false;
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return 0;
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}
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